It is often awkward to read the time of a place in a given time zone in a watch, due to the division into 24 time zones, which means that there is an angular sector of small amplitude for each time zone.
A conventional solution, as seen in EP Patent No 0 579 093 B1 in the name of Cie des Montres Longines, Francillon S. A., juxtaposes a display means comprising a twenty-four hour-circle with an ordinary twelve hour display and with a time zone ring, relative to which the display means is moveable, driven by a rotating ring completing one revolution in twenty-four hours. A correction mechanism enables the hour hand to be corrected directly and independently, via action on the time-setting stem, without any action on the rotating ring and without any effect on the universal time.
WO Patent No 2009/121699 in the name of Glaschütter Unhrenbetrieb GmbH discloses a complication for the display of time zones on a second time zone display, distinct from the main current time display, and for the display of half-time zones used in some states in the world. This mechanism differentiates between summer time and winter time, and comprises a day/night indicator connected to the second time zone display. A time zone indicator comprises a place ring and an index which are moveable in relation to each other. Time setting corrections are possible, either independently for the main display and the second display, or for both together. A manual place corrector enables the place ring to be rotated step by step without changing the status of the main display and of the second display.
DE Patent Application No 38 41 440 A1 in the name of Zimmerman discloses a universal watch with a stator carrying twelve zone discs, each corresponding to two diametrically opposite time zones and all pivotally mounted on the same diameter of the stator. A rotor which is driven by the movement and coaxial to this stator causes synchronous pivoting, which makes reading awkward, and does not allow the only time zone concerned by a date change to be clearly displayed at a given time.
In addition to being cumbersome, these mechanisms are often complex, and occupy a significant portion of the thickness of the movement.